The pop beauty admits tensions can sometimes flare up between her and Jules De Martino on tour and she isn't afraid to let her anger out during a performance.
She told BANG Showbiz: "There have been times where I have been singing 'That's Not My Name', then midway through I've turned around mid-song and hurled a load of abuse at Jules then carried on singing."
Although Jules thinks it's healthy for him and Katie to let their frustrations out, he insists its important to remain level-headed about any tour spats.
He said: "I think the worst thing with it being just the two of us is if we fall out then, well, we stay angry.
"It's not like there's four members where somebody can act as The Go between, so we're very aware that if the two of us hit a brick wall about decision making or something else, then we have to be careful that it doesn't get out of control and we can't do a gig that night because of the row."
To avoid unnecessary bust-ups, Jules claims he and Katie have started to blame their problems on their road crew.
He explained: "That's when our crew become really important, because the crew kind of act as band members in that sort of situation when the tension is high and we're starting to fall out, they step in and then we blame them instead."